PDA's - HP Ipaq or similar - Rate em?

Looking for a pda that can act as organiser and sat nav. have seen the following pre-used on ebay but haven't a notion, any advice? Smartphone function would be a plus !!

Ipaq HW6915 (smartphone), HW6515 (smartphone), HX2790, HX2490

Thanks

I have a 6915 which I no longer use as my primary phone. It has a good specification but can be horrendously slow and don't be surprised if you have to reset it frequently to get the GPS online. The main advantage is close integration with MS Outlook. The screen format is incompatible with the Garmin GPS software. But, a plus is that the screen is daylight readable.

My current phone is an HTC TyTyn II and while it's not perfect, screen cannot be read in direct sunlight, it's fast, has GPS, WiFi, Bluetooth, Camera, HSDPA and lots of memory and it generally rocks. I run TomTom on it.

I have a Blackberry 8310 and I find the GPS very good. It's still very big but I need the full screen for writing emails. It's integrated with Outlook. I travel alot and find it great that there's no BS about getting mails anywhere in the world.

I Second the TYTN II, it's a great machine and has all that you would need

Mik

Thanks folks - thats confirmed some of my reservations about IPAQ